This disclosure relates generally to tools located in a wellbore, and more particularly concerns a system and method of calibrating tools used to detect fluids and gases, and components thereof, in a downhole environment.
It is often desirable to monitor the properties of hydrocarbons retrieved from a subterranean formation in-situ. For instance, with respect to petroleum, it may be desirable to monitor a number of physical qualities, such as, for example: phase (oil, water, gas, solids), density, viscosity, bubble point, petroleum formation factor, and reservoir continuity. Other important fluid chemical properties that may be monitored in reservoir fluids include, for example: concentrations of methane, ethane, propane, butane, pentane, oxygen, CO2, H2S; GOR (gas oil ratio); saturate, aromatic, resin and asphaltene (SARA) composition; water content and chemistry (ions and pH); and other contaminants (e.g., mud filtrate).
However, the tools used to monitor hydrocarbons in a well are often not calibrated adequately to be able to make accurate measurements. This may be, for example, because the fluid or gas in the sample may not be at a concentration high enough to be measured, the fluid or gas in the measured sample may be below the limit of detection by the tool, or there may be contamination (e.g., from drilling fluid in the wellbore) in the sample that interferes with the instruments' detection method. Additionally, tools that are calibrated may need to be recalibrated once positioned downhole, to account for instrumental drift due to changes in temperature and pressure at which the tool must operate in the wellbore. Accordingly, it is desirable to be able to calibrate a tool in-situ to take measurements of a sample without needing to raise it to the surface.
The disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the disclosure being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.